Abnormality detection apparatus for resolver

ABSTRACT

To provide an abnormality detection apparatus for resolver which can determine the abnormality of at least the first system, even if the period of the excitation AC voltage of the first system and the period of the excitation AC voltage of the second system are different periods, and the magnetic interference between systems occurs. An abnormality detection apparatus for resolver applies an AC voltage of a first period to a first system excitation winding; applies an AC voltage of a second period different from the first period to a second system excitation winding; calculates a first system square sum which is a sum of square values of the detection values of output signals of first system two output windings after the second period component reduction processing: and determines abnormality of first system based on whether or not the first system square sum is within a normal range of first system.

TECHNICAL FIELD

The present disclosure is related with an abnormality detectionapparatus for resolver.

BACKGROUND ART

As the angle detection device which detects the rotational angle of themotor, the resolver is used well. Although the resolver is known as therobust angle detection device, the resolver is also required forredundancy from the request of the fault tolerance of the motor drivesystem.

Then, the patent document 1 discloses the dual system resolver which isprovided with the first system excitation winding and output winding,and the second system excitation winding and output winding.

The patent document 2 discloses the technology that the first and thesecond resolver sensors are provided, and it is determined that signalwires of both resolvers short-circuited, when the amplitude sin ωt ofthe output signal of sine phase and the amplitude cos ωt of the outputsignal of cosine phase do not satisfy the relation of (sin ωt)²+(cosωt)²=1 about each resolver sensor.

Although it does not have redundancy, the patent document 3 disclosesthe technology that, in the angle detection device which outputs thesine wave signal and the cosine wave signal according to the rotorposition of a brushless DC motor, failure of the angle detection deviceis detected based on whether or not the sum of each square value of thesine wave signal and the cosine wave signal becomes within thepredetermined range.

CITATION LIST Patent Literature

Patent document 1: JP 2000-18968 A

Patent document 2: JP 2005-147791 A

Patent document 3: JP 2006-335252 A

SUMMARY OF INVENTION Technical Problem

However, in the redundant system resolver like the patent document 1 and2, even if electrically insulated between the first system and thesecond system which configure the redundant system, a magneticinterference occurs. Accordingly, in the output signal of the outputwinding in one of the first system and the second system, a componentresulting from the excitation AC voltage in the other of the firstsystem and the second system is included. For example, in the outputsignal of the output winding in the first system, in addition to thecomponent resulting from the excitation AC voltage applied to the firstsystem excitation winding, the component resulting from the excitationAC voltage applied to the second system excitation winding is included.Similarly, also in the output signal of the output winding in the secondsystem, in addition to the component resulting from the excitation ACvoltage applied to the second system excitation winding, the componentresulting from the excitation AC voltage applied to the first systemexcitation winding is included.

The patent document 1 does not disclose the technology of determiningthe abnormality of each system, in this kind resolver which has thefirst system and the second system. The patent document 3 does notdisclose the technology of determining the abnormality of each system,in the redundant system resolver.

In the technology of patent document 2, the phases of the output signalsof the sine phase and the cosine phase of the first resolver, and thephases of the output signals of the sine phase and the cosine phase ofthe second resolver are different 180 degrees. The period of the ACvoltage applied to the excitation winding of the first resolver, and theperiod of the AC voltage applied to the excitation winding of the secondresolver are made the same periods. Accordingly, in the patent document2, although the influence of the magnetic interference between the firstsystem and the second system is not indicated, even if the magneticinterference occurs, the component resulting from the excitation windingof the first resolver and the component resulting from the excitationwinding of the second resolver, which are included in the output signalsof the sine phase and the cosine phase of the first resolver, becomeinverse phases. Accordingly, the amplitude gains of the output signalsof the sine phase and the cosine phase only decrease, but the relationof (sin ωt)²+(cos ωt)²=1 is maintained.

Therefore, like the technology of the patent document 2, if the periodof the AC voltage applied to the first system excitation winding and theperiod of the AC voltage applied to the second system excitation windingare the same periods, and the phases of the first system two outputsignals and the phases of the second system two output signals becomethe same phases or inverse phases, even if the magnetic interferencebetween systems occurs, it is thought that abnormality can be determinedbased on the square sum of two output signals, about each system.

However, if the period of the AC voltage applied to the first systemexcitation winding and the period of the AC voltage applied to thesecond system excitation winding are different periods, as mentionedabove, due to the component resulting from the excitation AC voltage ofthe second system included in the first system two output signals, therelation of (sin ωt)²+(cos ωt)²=1 is not established, and the vibrationcomponent of the period of the excitation AC voltage of the secondsystem is superimposed on the square sum of the first system two outputsignals. Accordingly, based on the square sum, abnormality of firstsystem cannot be determined with good accuracy. Similarly, based on thesquare sum of the second system two output signals, abnormality ofsecond system cannot be determined with good accuracy.

In order to improve redundancy, it is required to provide a resolver inwhich the first system and the second system can be operatedindependently with each other, the synchronization between theexcitation AC voltage of the first system and the excitation AC voltageof the second system is not required, and the period of the excitationAC voltage of the first system and the period of the excitation ACvoltage of the second system are different periods.

Then, the purpose of the present disclosure is to provide an abnormalitydetection apparatus for resolver which can determine the abnormality ofat least the first system, even if the period of the excitation ACvoltage of the first system and the period of the excitation AC voltageof the second system are different periods, and the magneticinterference between systems occurs.

Solution to Problem

An abnormality detection apparatus for resolver according to the presentdisclosure including:

a resolver that is provided with a first system excitation winding,first system two output windings, a second system excitation winding,and second system two output windings, in which magnetic interferenceoccurs between a first system and a second system;

a first system excitation unit that applies AC voltage of a first periodto the first system excitation winding;

a second system excitation unit that applies the AC voltage of a secondperiod different from the first period, to the second system excitationwinding;

a first system output signal detection unit that detects periodicallyoutput signals of the first system two output windings at preliminarilyset detection timing;

a first system reduction processing unit that performs a second periodcomponent reduction processing which reduces component of the secondperiod, to detection values of the output signals of the first systemtwo output windings;

a first system square sum calculation unit that calculates a firstsystem square sum which is a sum of square values of the detectionvalues of output signals of first system two output windings after thesecond period component reduction processing; and

a first system abnormality detection unit that determines abnormality offirst system, based on whether or not the first system square sum iswithin a preliminarily set normal range of first system.

Advantage of Invention

According to the abnormality detection apparatus for resolver of thepresent disclosure, even if the first period and the second period aredifferent, and the components of the second period resulting from theexcitation AC voltage of the second period of the second system due tothe magnetic interference between systems are included in the detectionvalues of output signals of first system two output windings, thecomponents of the second period can be reduced from the detection valuesof output signals of first system two output windings, by the secondperiod component reduction processing. Then, since the first systemsquare sum which is a sum of square values of the detection values ofoutput signals of first system two output windings after the secondperiod component reduction processing is calculated, it can besuppressed that the vibration component of the second period issuperimposed on the first system square sum. Accordingly, theabnormality of first system can be determined with good accuracy, basedon whether or not the first system square sum is within the normal rangeof first system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram of the abnormality detectionapparatus for resolver according to Embodiment 1;

FIG. 2 is a side view of the resolver viewed in the axial directionaccording to Embodiment 1;

FIG. 3 is a time chart for explaining the first system detection timingwhen supposing that there is no magnetic interference between systemsaccording to Embodiment 1;

FIG. 4 is a hardware configuration diagram of the controller accordingto Embodiment 1;

FIG. 5 is a time chart for explaining the second period componentreduction processing of the first system according to Embodiment 1;

FIG. 6 is a block diagram of the first system reduction processing unitaccording to Embodiment 1;

FIG. 7 is a flowchart explaining the abnormality detection processing ofthe first system according to Embodiment 1;

FIG. 8 is a flowchart explaining another example of the abnormalitydetection processing of the first system according to Embodiment 1;

FIG. 9 is a time chart for explaining the first period componentreduction processing of the second system according to Embodiment 1;

FIG. 10 is a block diagram of the second system reduction processingunit according to Embodiment 1;

FIG. 11 is a flowchart explaining the abnormality detection processingof the second system according to Embodiment 1;

FIG. 12 is a flowchart explaining another example of the abnormalitydetection processing of the second system according to Embodiment 1;

FIG. 13 is a time chart for explaining the first period componentreduction processing of the second system according to Embodiment 2;

FIG. 14 is a block diagram of the second system reduction processingunit according to Embodiment 2;

FIG. 15 is a schematic configuration diagram of the abnormalitydetection apparatus for resolver according to Embodiment 3; and

FIG. 16 is a schematic perspective view of the resolver according toEmbodiment 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS 1. Embodiment 1

An abnormality detection apparatus for resolver according to Embodiment1 is explained with reference to drawings. FIG. 1 is a schematicconfiguration diagram of the abnormality detection apparatus forresolver according to the present embodiment. The abnormality detectionapparatus for resolver is also an angle detection apparatus.

1-1. Resolver 1

The resolver 1 is provided with a first system excitation winding 10A,first system two output windings 111A, 112A (referred to also as a firstsystem first output winding 111A and a first system second outputwinding 112A), a second system excitation winding 10B, and second systemtwo output windings 111B, 112B (referred to also as a second systemfirst output winding 111B and a second system second output winding112B). A magnetic interference occurs between the first system windingsand the second system windings. That is to say, by electromagneticinduction due to the magnetic flux generated by the first systemexcitation winding 10A, an induced voltage is generated not only in thefirst system two output windings 111A, 112A, but also in the secondsystem two output windings 111B, 112B; and by electromagnetic inductiondue to the magnetic flux generated by the second system excitationwinding 10B, an induced voltage is generated not only in the secondsystem two output windings 111B, 112B, but also in the first system twooutput windings 111A, 112A.

As shown in FIG. 2 , the first system excitation winding 10A, the firstsystem two output windings 111A, 112A, the second system excitationwinding 10B, and second system two output windings 111B, 112B are woundaround the same one stator 13. The rotor 14 is arranged in theradial-direction inner side of the stator 13. The rotor 14 is providedwith a plurality of projection parts which are arranged equally in thecircumferential direction on the peripheral part of the rotor. Theprojection height to the radial-direction outside of the projectionparts is formed so that the gap permeance between the stator 13 and therotor 14 changes in sine wave shape according to rotation. That is tosay, the resolver 1 is a variable reluctance (VR) type resolver. In thepresent embodiment, the five projection parts are provided, and theshaft angle multiplier is 5. Therefore, whenever the rotor rotates oncein the mechanical angle, rotates 5 times in the electrical angle.

As showing an example supposed that there is no magnetic interferencebetween two systems in FIG. 3 , when the rotor rotates in the statewhere the AC voltage VRA is applied to the first system excitationwinding 10A, the amplitude of AC voltage V1A induced by the first systemfirst output winding 111A and the amplitude of AC voltage V2A induced bythe first system second output winding 112A change in a sine wave shape(or in a cosine wave shape), according to the rotational angle (the gappermeance) in the electrical angle of the rotor. The first system firstoutput winding 111A and the first system second output winding 112A arewound around the positions of the circumferential direction of thestator 13 so that the amplitudes of those AC voltages are mutuallydifferent 90 degrees in the electrical angle. Similarly, the secondsystem first output winding 111B and the second system second outputwinding 112B are wound around the positions of the circumferentialdirection of the stator 13 so that the amplitudes of those induced ACvoltages are mutually different 90 degrees in the electrical angle.

In the present embodiment, as shown in FIG. 2 , the stator 13 isprovided with 12 teeth arranged equally in the circumferentialdirection; the first system windings are wound around the first teethTE1 to the sixth teeth TE6; and the second system windings are woundaround the seventh teeth TE7 to the twelfth teeth TE12. The first systemexcitation winding 10A is distributed and wound around the first teethTE1 to the sixth teeth TE6. The first system first output winding 111Aand the first system second output winding 112A are distributed andwound around the first teeth TE1 to the sixth teeth TE6 so that theamplitudes of those induced AC voltages are mutually different 90degrees in the electrical angle. Similarly, the second system excitationwinding 10B is distributed and wound around the seventh teeth TE7 to thetwelfth teeth TE12. The second system first output winding 111B and thesecond system second output winding 112B are distributed and woundaround the seventh teeth TE7 to the twelfth teeth TE12 so that theamplitudes of those induced AC voltages are mutually different 90degrees in the electrical angle.

The first system excitation winding 10A wound around the plurality ofteeth is connected in series between teeth; and the two terminals of thefirst system excitation winding 10A connected in series are connected tothe controller 50 (the first system excitation unit 51A) describedbelow. Similarly, the two terminals of the first system first outputwinding 111A connected in series between teeth are connected to thecontroller 50 (the first system output signal detection unit 52A)described below. The two terminals of the first system second outputwinding 112A connected in series between teeth are connected to thecontroller 50 (the first system output signal detection unit 52A)described below. The two terminals of the second system excitationwinding 10B wound around the plurality of teeth are connected to thecontroller 50 (the second system excitation unit 51B) described below.Similarly, the two terminals of the second system first output winding111B connected in series between teeth are connected to the controller50 (the second system output signal detection unit 52B) described below.The two terminals of the second system second output winding 112Bconnected in series between teeth are connected to the controller 50(the second system output signal detection unit 52B) described below.

The number of projection parts (shaft angle multiplier) and the numberof teeth may be set to any numbers. The first system windings and thesecond system windings may not be arranged being divided into two in thecircumferential direction, but may be arranged being distributed in thecircumferential direction.

1-2. Controller 50

The abnormality detection apparatus for resolver is provided with acontroller 50. As shown in FIG. 1 , the controller 50 is provided with afirst system excitation unit 51A, a first system output signal detectionunit 52A, a first system reduction processing unit 53A, a first systemangle calculation unit 54A, a first system square sum calculation unit55A, a first system abnormality detection unit 56A, a second systemexcitation unit 51B, a second system output signal detection unit 52B, asecond system reduction processing unit 53B, a second system anglecalculation unit 54B, a second system square sum calculation unit 55B,and a second system abnormality detection unit 56B. Each function of thecontroller 50 is realized by processing circuits provided in thecontroller 50.

Specifically, as shown in FIG. 4 , the controller 50 includes, as aprocessing circuit, a arithmetic processor (computer) 90 such as a CPU(Central Processing Unit), storage apparatuses 91 which exchange datawith the arithmetic processor 90, an input circuit 92 which inputsexternal signals to the arithmetic processor 90, an output circuit 93which outputs signals from the arithmetic processor 90 to the outside,and the like.

As the arithmetic processor 90, ASIC (Application Specific IntegratedCircuit), IC (Integrated Circuit), DSP (Digital Signal Processor), FPGA(Field Programmable Gate Array), various kinds of logical circuits,various kinds of signal processing circuits, and the like may beprovided. As the arithmetic processor 90, a plurality of the same typeones or the different type ones may be provided, and each processing maybe shared and executed. As the storage apparatuses 91, there areprovided a RAM (Random Access Memory) which can read data and write datafrom the arithmetic processor 90, a ROM (Read Only Memory) which canread data from the arithmetic processor 90, and the like. The firstsystem first output winding 111A, the first system second output winding112A, the second system first output winding 111B, and the second systemsecond output winding 112B are connected to the input circuit 92. Theinput circuit 92 is provided with an A/D converter and the like forinputting the output voltages of these windings into the arithmeticprocessor 90. The output circuit 93 is connected with the first systemexcitation winding 10A and the second system excitation winding 10B, andis provided with driving circuits, such as switching devices forapplying the AC voltage VRA to these windings. A lowpass filter circuitmay be provided in the output side of the switching device. The outputcircuit 93 is provided with signal output circuits, such as acommunication circuit which transmits the first angle θ1, the secondangle θ2, the first system abnormality signal ERR1, and the secondsystem abnormality signal ERR2 which were calculated to the externalcontroller 94.

Then, the arithmetic processor 90 runs software items (programs) storedin the storage apparatus 91 such as a ROM and collaborates with otherhardware devices in the controller 50, such as the storage apparatus 91,the input circuit 92, and the output circuit 93, so that the respectivefunctions of the control units 51A to 56B included in the controller 50are realized. Setting data utilized in the control units 51A to 56B arestored, as part of software items (programs), in the storage apparatus91 such as a ROM. Each function of the controller 50 will be describedin detail below.

1-2-1. Excitation Unit

The first system excitation unit 51A applies AC voltage VRA (in thisexample, AC voltage VRA of a sine wave) of first period TA to the firstsystem excitation winding 10A. The first system excitation unit 51Acalculates an AC voltage command of the first period TA, and generatesthe PWM signal (Pulse Width Modulation) which turns on and off theswitching device for the first system excitation winding provided in theoutput circuit 93, based on the comparison result between the AC voltagecommand and the triangular wave. When the switching device is turned on,the power source voltage is applied to the first system excitationwinding 10A side, and when the switching device is turned off, theapplication of the power source voltage stops.

The second system excitation unit 51B applies AC voltage VRB (in thisexample, AC voltage VRB of a sine wave) of second period TB to thesecond system excitation winding 10B. The second period TB is set to aperiod different from the first period TA. In the present embodiment, asdescribed later, the second period TB is set to two times of the firstperiod TA (TB=2×TA). For example, in the case of TA=50 microseconds, itis set as TB=100 microseconds.

The second system excitation unit 51B calculates an AC voltage commandof the second period TB, and generates the PWM signal (Pulse WidthModulation) which turns on and off the switching device for the secondsystem excitation winding provided in the output circuit 93, based onthe comparison result between the AC voltage command and the triangularwave.

1-2-2. First System Output Signal Detection Unit

The first system output signal detection unit 52A detects periodicallythe output signals V1A, V2A of the first system two output windings111A, 112A at preliminarily set detection timing (hereinafter, referredto also as the first system detection timing).

1-2-3. First System Reduction Processing Unit <Problem Due to MagneticInterference Between Systems>

As showing an example of the output signal V1A of the first system firstoutput winding in FIG. 5 , the components of the second period V1A_TB,V2A_TB induced by electromagnetic induction due to the magnetic flux ofthe second period TB excited in the second system excitation winding 10Bare superimposed on each of the output signals V1A, V2A of the firstsystem two output windings 111A, 112A, due to the magnetic interferencebetween systems. The output signal V1A of the first system first outputwinding is shown in the upper row graph of FIG. 5 ; the component of thefirst period V1A_TA induced by electromagnetic induction due to themagnetic flux of the first system excitation winding 10A included in theoutput signal V1A of the first system first output winding is shown inthe middle graph; and the component of the second period V1A_TB inducedby electromagnetic induction due to the magnetic flux of the secondsystem excitation winding 10B included in the output signal V1A of thefirst system first output winding is shown in the lower row graph. Theoutput signal V1A of first system first output winding becomes a signalobtained by totaling the component of the first period V1A_TA and thecomponent of the second period V1A_TB.

<Second Period Component Reduction Processing>

Then, the first system reduction processing unit 53A performs a secondperiod component reduction processing which reduces component of thesecond period, to the detection values of output signals of first systemtwo output windings V1A_S, V2A_S. Then, the first system square sumcalculation unit 55A described below calculates a first system squaresum V1_amp which is a sum of square values of the detection values ofoutput signals of first system two output windings V1A_F, V2A_F afterthe second period component reduction processing.

In the present embodiment, the first period component reductionprocessing is performed based on a principle explained in the following.As shown in the lower row graph of FIG. 5 , in the component of thesecond period V1A_TB of the output signal of the first system firstoutput winding, the phase is reversed and the sign of plus or minus isreversed at a period (for example, half period TB/2 of the secondperiod) obtained by adding an integral multiple of the second period TBto a half period TB/2 of the second period.

Then, as the second period component reduction processing, the firstsystem reduction processing unit 53A adds the detection values of outputsignals of first system two output windings V1A_S, V2A_S detected atthis time detection timing, and the detection values of output signalsof first system two output windings V1A_Sold, V2A_Sold detected at adetection timing earlier by the first system reduction processinginterval ΔT1 than this time detection timing. The first system reductionprocessing interval ΔT1 is set as shown in the next equation. Herein, Mis an integer greater than or equal to 0. In the present embodiment, Mis set to 0, and the first system reduction processing interval ΔT1 isset to the half period TB/2 of the second period.

ΔT1=TB/2+TB×M  (1)

The first system reduction processing unit 53A is constituted, forexample, as shown in FIG. 6 . The first system reduction processing unit53A is provided with a first delay device 53A1 which delays thedetection value V1A_S of the output signal of the first system firstoutput winding by the first system reduction processing interval ΔT1,and outputs; adds the detection value V1A_S of the output signal of thefirst system first output winding, and the output V1A_Sold of the firstdelay device 53A1; and calculates the detection value V1A_F of theoutput signal of the first system first output winding after the secondperiod component reduction processing. Similarly, the first systemreduction processing unit 53A is provided with a second delay device53A2 which delays the detection value V2A_S of the output signal of thefirst system second output winding by the first system reductionprocessing interval ΔT1, and outputs; adds the detection value V2A_S ofthe output signal of the first system second output winding, and theoutput V2A_Sold of the second delay device 53A2; and calculates thedetection value V2A_F of the output signal of the first system secondoutput winding after the second period component reduction processing.

Then, the first system square sum calculation unit 55A calculates thefirst system square sum V1_amp which is a sum of square values of thedetection values of output signals of first system two output windingsV1A_F, V2A_F after the second period component reduction processing.

According to this configuration, the two components of the second periodwhose signs of plus or minus are reversed with each other are added, andthe two components of the second period are canceled with each other.Accordingly, in the detection values of output signals of first systemtwo output windings V1A_F, V2A_F after addition, the component of thesecond period is reduced. Then, using the components of the first periodof the first system in which the component of the second period of thesecond system was reduced, the first system square sum V1_amp used forfirst system abnormality determination can be calculated with goodaccuracy.

In the present embodiment, the second period TB is set to an evenmultiple of the first period TA, as shown in the next equation. Herein,N is an integer greater than or equal to 1. In the present embodiment, Nis set to 1, and the second period TB is set to a twice of the firstperiod TA. For example, if the first period TA is set to 50microseconds, the second period TB is set to 100 microseconds.

TB=TA×2×N  (2)

According to this configuration, as shown in the next equation in whichthe equation (2) is substituted in the equation (1), the first systemreduction processing interval ΔT1 becomes an integral multiple of thefirst period TA.

ΔT1=TA×(N+2×N×M)  (3)

Therefore, among the detection values of output signals of first systemtwo output windings V1A_S, V2A_S, values before and after the integralmultiple of the first period TA are added. Then, as shown in FIG. 5 ,since the added two components of the first period have the same phase,and become the equivalent values with the same sign of plus or minus,the detection values of output signals of first system two outputwindings V1A_F, V2A_F after addition correspond to the double values ofthe components of the first period V1A_TA, V2A_TA included in thedetection values, respectively.

V1A_F≈2×V1A_TA

V2A_F≈2×V2A_TA  (4)

Accordingly, in the equation (5) and the equation (6) described below,since a square value of the detection value V1A_F of the output signalof the first system first output winding after addition and a squarevalue of the detection value V2A_F of the output signal of the firstsystem second output winding after addition are added, it corresponds toa 4 times value of the square sum of the components of the first periodV1A_TA, V2A_TA, and the first system square sum V1_amp can be calculatedwith good accuracy, based on the components of the first period of thefirst system in which the components of the second period of the secondsystem were reduced.

In the present embodiment, M is set to 0, and N is set to 1. Therefore,the first system reduction processing unit 53A adds the detection valuesof output signals of first system two output windings V1A_S, V2A_Sdetected at this time detection timing, and the detection values ofoutput signals of first system two output windings V1A_Sold, V2A_Solddetected before the first period TA (the half period TB/2 of the secondperiod).

In the present embodiment, the first system output signal detection unit52A detects the output signals V1A, V2A of the first system two outputwindings at a timing when the AC voltage VRA of the first period TAapplied to the first system excitation winding 10A becomes the maximumvalue or the minimum value (in this example, the maximum value). Thefirst system output signal detection unit 52A detects the output signalsV1A, V2A of the first system two output windings at every the firstperiod TA when the AC voltage VRA becomes the maximum value. That is tosay, the first system detection timing is set to the timing at every thefirst period TA.

FIG. 3 shows an example in which unlike the present embodiment, there isno magnetic interference between systems, and the component of thesecond period is not superimposed on the output signals V1A, V2A of thefirst system two output windings. At every the first period TA when theAC voltage VRA of the first period TA becomes the maximum value, theoutput signals V1A, V2A of the first system two output windings aredetected. Therefore, the component of the first period included in thedetection values of the output signals of the first system two outputwindings becomes the maximum value or the minimum value of the componentof the first period which is vibrating at the first period TA.Therefore, the amplitude of the component of the first period includedin the detection values of the output signals of the first system twooutput windings can be maximized, the detection sensitivity of thecomponent of the first period to the noise component can be increased,and the detection accuracy can be increased. The first system outputsignal detection unit 52A may detect the output signals V1A, V2A of thefirst system two output windings at the timing when the AC voltage VRAof the first period TA becomes other than the maximum value or theminimum value, excepting the timing when the AC voltage VRA of the firstperiod TA becomes the vibration center value (node).

1-2-4. First System Square Sum Calculation Unit

The first system square sum calculation unit 55A calculates the firstsystem square sum V1_amp which is a sum of square values of thedetection values of output signals of first system two output windingsV1A_F, V2A_F after the second period component reduction processing, asshown in the next equation.

V1_amp=V1A_F ² +V2A_F ²  (5)

As shown in the equation (4), the detection values of output signals ofthe first system two output windings V1A_F, V2A_F after the secondperiod component reduction processing correspond to the double values ofthe components of the first period V1A_TA, V2A_TA included in thedetection values, respectively. Therefore, as shown in the next equationin which the equation (4) is substituted in the equation (5), itcorresponds to a 4 times value of the square sum of the components ofthe first period V1A_TA, V2A_TA. Therefore, using the components of thefirst period V1A_TA, V2A_TA of the first system in which the componentof the second period V1A_TB, V2A_TB of the second system was reduced,the first system square sum V1_amp used for first system abnormalitydetermination can be calculated with good accuracy.

$\begin{matrix}\begin{matrix}{{V1{\_ amp}} \approx {( {2 \times V1{A\_ TA}} )^{2} + ( {2 \times V2{A\_ TA}} )^{2}}} \\{= {4 \times \{ {{V1{A\_ TA}^{2}} + {V2{A\_ TA}^{2}}} \}}}\end{matrix} & (6)\end{matrix}$

1-2-5. First System Abnormality Detection Unit

The first system abnormality detection unit 56A determines abnormalityof first system, based on whether or not the first system square sumV1_amp is within a preliminarily set normal range of first system.

As explained using FIG. 3 and the like, as shown in the next equation,if the first system is normal, the component of the first period V1A_TAoutputted from the first system first output winding 111A becomes a sinewave signal according to the angle θ1 in the electrical angle of therotor, and the component of the first period V2A_TA outputted from thefirst system second output winding 112A becomes a cosine wave signalaccording to the angle θ1 in the electrical angle of the rotor. Herein,KA1 is a prescribed constant related to induced voltage.

V1A_TA=KA1×sin(θ1)

V2A_TA=KA1×cos(θ1)  (7)

Accordingly, as shown in the next equation in which the equation (7) issubstituted in the equation (6), if the first system is normal, thefirst system square sum V1_amp becomes a prescribed value (normalvalue). Accordingly, when the first system square sum V1_amp deviatesfrom the normal range including the normal value, it can be determinedthat abnormality occurred in the first system.

$\begin{matrix}\begin{matrix}{{V1{\_ amp}} \approx {4 \times \{ {( {{KA}1 \times {\sin({\theta 1})}} )^{2} + ( {{KA}1 \times {\cos({\theta 1})}} )^{2}} \}}} \\{= {4 \times {KA}1^{2} \times \{ {{\sin({\theta 1})}^{2} + {\cos({\theta 1})}^{2}} \}}} \\{= {4 \times {KA}1^{2} \times 1}}\end{matrix} & (8)\end{matrix}$

On the other hand, in the case where the second period componentreduction processing (addition processing) is not performed unlike thepresent embodiment, and the components of the second period aresuperimposed on the detection values of output signals of first systemtwo output windings, as shown in FIG. 5 , since the phases of componentsof the second period are reversed at every first system detectiontiming, a vibration component of the second period TB is superimposed onthe first system square sum V1_amp, and the first system abnormalitydetermination cannot be performed with good accuracy.

The abnormality of first system includes abnormality of disconnection ofeach winding 10A, 111A, 112A of the first system, abnormality of theinput and output circuit of each winding of the first system in thecontroller 50, abnormality of processing related to the first system ofthe controller 50, and the like.

The normal range of first system is set to a range between a lower limitvalue of first system MIN1 and an upper limit value of first system MAX1in which a normal value of the first system square sum V1_amp isincluded. For example, the lower limit value of first system MIN1 ispreliminarily set to a value obtained by multiplying a coefficient (forexample, 0.9) smaller than 1 to the normal value of the first systemsquare sum V1_amp; and the upper limit value of first system MAX1 ispreliminarily set to a value obtained by multiplying a coefficient (forexample, 1.1) larger than 1 to the normal value of the first systemsquare sum V1_amp. The normal range of first system is adjusted inaccordance with the degree of abnormality to be determined as abnormal.

Processing of the abnormality determination is explained using theflowchart of FIG. 7 . Processing of the flowchart of FIG. 7 is executedafter calculating the first system square sum V1_amp at every the firstsystem detection timing.

In the step S01, the first system abnormality detection unit 56Aacquires the first system square sum V1_amp calculated by the firstsystem square sum calculation unit 55A. Then, in the step S02, the firstsystem abnormality detection unit 56A determines whether or not thefirst system square sum V1_amp is greater than or equal to the lowerlimit value of first system MIN1, and is less than or equal to the upperlimit value of first system MAX1. That is to say, the first systemabnormality detection unit 56A determines whether or not the firstsystem square sum V1_amp is within the normal range of first system.

When the first system abnormality detection unit 56A determines that thefirst system square sum V1_amp is not within the normal range of firstsystem in the step S02, it advances to the step S03 and determines thatthe abnormality of first system occurred. In the present embodiment, thefirst system abnormality detection unit 56A outputs a first systemabnormality signal ERR1, when determining that the abnormality of firstsystem occurred. For example, the first system abnormality signal ERR1is transmitted to the external controller 94 to which the first angle θ1is transmitted. If the controller 50 and the external controller 94 areintegrated, the first system abnormality signal ERR1 is transmitted inthe same controller.

On the other hand, when the first system abnormality detection unit 56Adetermines that the first system square sum V1_amp is within the normalrange of first system in the step S02, it determines that theabnormality of first system does not occur, and ends processing.

<Another Example of Abnormality Determination Processing>

Another example of processing of abnormality determination is explainedusing the flowchart of FIG. 8 . Processing of the flowchart of FIG. 8 isexecuted after calculating the first system square sum V1_amp at everythe first system detection timing.

In the step S11, the first system abnormality detection unit 56Aacquires the first system square sum V1_amp calculated by the firstsystem square sum calculation unit 55A. Then, in the step S12, the firstsystem abnormality detection unit 56A determines whether or not thefirst system square sum V1_amp is greater than or equal to the lowerlimit value of first system MIN1, and is less than or equal to the upperlimit value of first system MAX1. That is to say, the first systemabnormality detection unit 56A determines whether or not the firstsystem square sum V1_amp is within the normal range of first system.

When the first system abnormality detection unit 56A determines that thefirst system square sum V1_amp is not within the normal range of firstsystem in the step S12, it advances to the step S13 and increases theabnormality determination counter T1 by one. After that, it advances tothe step S14, and the first system abnormality detection unit 56Adetermines whether or not the abnormality determination counter T1 isgreater than or equal to a preliminarily set abnormality determinationfrequency T1 ab.

When the first system abnormality detection unit 56A determines that theabnormality determination counter T1 is greater than or equal to theabnormality determination frequency T1 ab in the step S14, it advancesto the step S15 and determines that the abnormality of first systemoccurred. Then, the first system abnormality detection unit 56A outputsthe first system abnormality signal ERR1, when determining that theabnormality of first system occurred. When the first system abnormalitydetection unit 56A determines that the abnormality determination counterT1 is not greater than or equal to the abnormality determinationfrequency T1 ab in the step S14, it determines that the abnormality offirst system does not occur, and ends processing.

On the other hand, when the first system abnormality detection unit 56Adetermines that the first system square sum V1_amp is within the normalrange of first system in the step S12, it advances to the step S16,after resetting the abnormality determination counter T1 to 0, endsprocessing.

In the example of the flowchart of FIG. 8 , when a case where the firstsystem square sum V1_amp is not within the normal range of first systemoccurs continuously the preliminarily set abnormality determinationfrequency T1 ab or more, the first system abnormality detection unit 56Adetermines that abnormality occurred in the first system.

In this way, by performing determination by the abnormalitydetermination frequency T1 ab, erroneous determination can be preventedfrom occurring due to noise component generated in the first systemsquare sum V1_amp. By determining that abnormality occurred when it isnot within the normal range continuously, accuracy of abnormalitydetermination can be improved.

In the step S16, the first system abnormality detection unit 56A may notreset the abnormality determination counter T1 to 0, but may hold theabnormality determination counter T1 to the previous value, or maydecrease the abnormality determination counter T1.

1-2-6. First System Angle Calculation Unit

As shown in the next equation, the first system angle calculation unit54A calculates the first angle θ1 by calculating an arc tangent (an arctangent function) of a ratio between the output signal V1A_F of thefirst system first output winding and the output signal V2A_F of thefirst system second output winding after the second period componentreduction processing.

θ1=tan⁻¹(V1A_F/V2A_F)  (9)

As shown in the equation (4), the detection values of output signals ofthe first system two output windings V1A_F, V2A_F after the secondperiod component reduction processing correspond to the double values ofthe components of the first period V1A_TA, V2A_TA included in thedetection values, respectively. Therefore, as shown in the next equationin which the equation (4) is substituted in the equation (9), the firstangle θ1 is calculated with good accuracy by the ratio of the componentsof the first period V1A_TA, V2A_TA included in the detection values.

$\begin{matrix}{{{\theta 1} \approx {\tan^{- 1}\{ {( {2 \times V1{A\_ TA}} )/( {2 \times V2{A\_ TA}} )} \}}} = {\tan^{- 1}( {{V1A\_ TA}/{V2A\_ TA}} )}} & (10)\end{matrix}$

1-2-6. Second System Output Signal Detection Unit

The second system output signal detection unit 52B detects periodicallythe output signals V1B, V2B of the second system two output windings111B, 112B at preliminarily set detection timing (hereinafter, referredto also as the second system detection timing).

1-2-8. Second System Reduction Processing Unit <Problem Due to MagneticInterference Between Systems>

As showing an example of the output signal V1B of the second systemfirst output winding in FIG. 9 , the components of the first periodinduced by the magnetic flux of the first period TA excited in the firstsystem excitation winding 10A are superimposed on each of the outputsignals V1B, V2B of the second system two output windings 111B, 112B,due to the magnetic interference between systems. The output signal V1Bof the second system first output winding is shown in the upper rowgraph of FIG. 9 ; the component of the second period V1B_TB induced byelectromagnetic induction of the magnetic flux of the second systemexcitation winding 10B included in the output signal V1B of the secondsystem first output winding is shown in the middle graph; and thecomponent of the first period V1B_TA induced by electromagneticinduction of the magnetic flux of the first system excitation winding10A included in the output signal V1B of the second system first outputwinding is shown in the lower row graph. The output signal V1B of secondsystem first output winding becomes a signal obtained by totaling thecomponent of the second period V1B_TB and the component of the firstperiod V1B_TA.

<First Period Component Reduction Processing>

Then, the second system reduction processing unit 53B performs a firstperiod component reduction processing which reduces component of thefirst period, to the detection values of output signals of second systemtwo output windings V1B_S, V2B_S. Then, the second system square sumcalculation unit 55B described below calculates a second system squaresum V2_amp which is a sum of square values of the detection values ofoutput signals of second system two output windings V1B_F, V2B_F afterthe first period component reduction processing.

In the present embodiment, the first period component reductionprocessing is performed based on a principle explained in the following.As shown in the lower row graph of FIG. 9 , the component of the firstperiod V1B_TA of the output signal of second system first output windingbecomes the same value at every first period TA, since its period is thefirst period TA.

Then, as the first period component reduction processing, the secondsystem reduction processing unit 53B performs a subtraction processingthat calculates differences between the detection values of outputsignals of second system two output windings V1B_S, V2B_S detected atthis time detection timing, and the detection values of output signalsof second system two output windings V1B_Sold, V2B_Sold detected at thedetection timing earlier by the second system reduction processinginterval ΔT2 than this time detection timing. The second systemreduction processing interval ΔT2 is set to an integral multiple of thefirst period TA, as shown in the next equation. Herein, P is an integergreater than or equal to 1. In the present embodiment, P is set to 1,and the second system reduction processing interval ΔT2 is set to thefirst period TA.

ΔT2=TA×P  (11)

The second system reduction processing unit 53B is constituted, forexample, as shown in FIG. 10 . The second system reduction processingunit 53B is provided with a first delay device 53B1 which delays thedetection value V1B_S of the output signal of the second system firstoutput winding by the second system reduction processing interval ΔT2,and outputs; subtracts the output V1B_Sold of the first delay device53B1 from the detection value V1B_S of the output signal of the secondsystem first output winding; and calculates the detection value V1B_F ofthe output signal of the second system first output winding after thefirst period component reduction processing. Similarly, the secondsystem reduction processing unit 53B is provided with a second delaydevice 53B2 which delays the detection value V2B_S of the output signalof the second system second output winding by the second systemreduction processing ΔT2, and outputs; subtracts the output V2B_Sold ofthe second delay device 53B2 from the detection value V2B_S of theoutput signal of the second system second output winding; and calculatesthe detection value V2B_F of the output signal of the second outputwinding after the first period component reduction processing.

Then, the second system square sum calculation unit 55B calculates thesecond system square sum V2_amp which is a sum of square values of thedetection values of output signals of second system two output windingsV1B_F, V2B_F after the first period component reduction processing.

According to this configuration, the two components of the first periodwhich become the equivalent values with the same sign of plus or minuswith each other are subtracted, and the two components of the firstperiod are canceled with each other. Accordingly, in the detectionvalues of output signals of second system two output windings V1B_F,V2B_F after the subtraction processing, the component of the firstperiod is reduced. Then, using the components of the second period ofthe second system in which the component of the first period of thefirst system was reduced, the second system square sum V2_amp used forsecond system abnormality determination can be calculated with goodaccuracy.

As mentioned above, in the present embodiment, the second period TB isset to an even multiple of the first period TA, as shown in the nextequation. Herein, N is an integer greater than or equal to 1. In thepresent embodiment, N is set to 1, and the second period TB is set to atwice of the first period TA.

TB=TA×2×N  (12)

The second reduction processing ΔT2 is set as shown in the nextequation. Herein, L is an integer greater than or equal to 0. In thepresent embodiment, L is set to 0, and the second system reductionprocessing interval ΔT2 is set to the half period TB/2 of the secondperiod.

ΔT2=TB/2+TB×L  (13)

Even in this case, if the equation (12) is substituted in the equation(13), the second system reduction processing interval ΔT2 becomes anintegral multiple of the first period TA similarly to the equation (11),as shown in the next equation. Therefore, as mentioned above, by thefirst period component reduction processing (the subtractionprocessing), the components of the first period can be reduced.

ΔT2=TA×N×(1+2×L)  (14)

By setting the second system reduction processing interval ΔT2 like theequation (13), in the two components of the second period subtracted bythe subtraction processing, the phases are reversed and the signs ofplus or minus are reversed, as shown in FIG. 9 . Therefore, thedetection values of output signals of second system two output windingsV1B_F, V2B_F after the subtraction processing correspond to the doublevalues of the components of the second period V1B_TB, V2B_TB included inthe detection values, respectively.

V1B_F≈2×V1B_TB

V2B_F≈2×V2B_TB  (15)

Accordingly, in the equation (16) and the equation (17) described below,since a square value of the detection value V1B_F of the output signalof the second system first output winding after subtraction processingand a square value of the detection value V2B_F of the output signal ofthe second system second output winding after subtraction processing areadded, it corresponds to a 4 times value of the square sum of thecomponents of the second period V1B_TB, V2B_TB, and the second systemsquare sum V2_amp can be calculated with good accuracy, based on thecomponents of the second period of the second system in which thecomponents of the first period of the first system were reduced.

In the present embodiment, L is set to 0, N is set to 1, and P is setto 1. Therefore, the second system reduction processing unit 53Bsubtracts the detection values of output signals of second system twooutput windings V1B_Sold, V2B_Sold detected before the half period TB/2of the second period (the first period TA), from the detection values ofoutput signals of second system two output windings V1B_S, V2B_Sdetected at this time detection timing.

In the present embodiment, the second system output signal detectionunit 52B detects the output signals V1B, V2B of the second system twooutput windings at a timing when the AC voltage VRB of the second periodTB applied to the second system excitation winding 10B becomes themaximum value or the minimum value. The second system output signaldetection unit 52B detects the output signals V1B, V2B of the secondsystem two output windings at every the half period TB/2 of the secondperiod when the AC voltage VRB becomes the maximum value or the minimumvalue.

According to this configuration, similar to the first system, thecomponent of the second period included in the detection values of theoutput signals of the second system two output windings becomes themaximum value or the minimum value of the component of the second periodwhich is vibrating at the second period TB. Therefore, the amplitude ofthe component of the second period included in the detection values ofthe output signals of the second system two output windings can bemaximized, the detection sensitivity of the component of the secondperiod to the noise component can be increased, and the detectionaccuracy can be increased. The second system output signal detectionunit 52B may detect the output signals V1B, V2B of the second system twooutput windings at the timing when the AC voltage VRB of the secondperiod TB becomes other than the maximum value or the minimum value,excepting the timing when the AC voltage VRB of the second period TBbecomes the vibration center value (node).

1-2-9. Second System Square Sum Calculation Unit

The second system square sum calculation unit 55B calculates the secondsystem square sum V2_amp which is a sum of square values of thedetection values of output signals of second system two output windingsV1B_F, V2B_F after the first period component reduction processing, asshown in the next equation.

V2_amp=V1B_F ² +V2B_F ²  (16)

As shown in the equation (15), the detection values of output signals ofthe second system two output windings V1B_F, V2B_F after the firstperiod component reduction processing correspond to the double values ofthe components of the second period V1B_TB, V2B_TB included in thedetection values, respectively. Therefore, as shown in the next equationin which the equation (15) is substituted in the equation (16), itcorresponds to a 4 times value of the square sum of the components ofthe second period V1B_TB, V2B_TB. Therefore, using the components of thesecond period V1B_TB, V2B_TB of the second system in which the componentof the first period V1B_TA, V2B_TA of the first system was reduced, thesecond system square sum V2_amp used for second system abnormalitydetermination can be calculated with good accuracy.

$\begin{matrix}\begin{matrix}{{V2\_ amp} \approx {( {2 \times {V1B\_ TB}} )^{2} + ( {2 \times {V2B\_ TB}} )^{2}}} \\{= {4 \times \{ {{V1B\_ TB}^{2} + {V2B\_ TB}^{2}} \}}}\end{matrix} & (17)\end{matrix}$

1-2-10. Second System Abnormality Detection Unit

The second system abnormality detection unit 56B determines abnormalityof second system, based on whether or not the second system square sumV2_amp is within a preliminarily set normal range of second.

Similarly to the first system, as shown in the next equation, if thesecond system is normal, the component of the second period V1B_TBoutputted from the second system first output winding 111B becomes asine wave signal according to the angle θ2 in the electrical angle ofthe rotor, and the component of the second period V2B_TB outputted fromthe second system second output winding 112B becomes a cosine wavesignal according to the angle θ2 in the electrical angle of the rotor.Herein, KA2 is a prescribed constant related to induced voltage.

V1B_TB=KA2×sin(θ2)

V2B_TB=KA2×cos(θ2)  (18)

Accordingly, as shown in the next equation in which the equation (18) issubstituted in the equation (17), if the second system is normal, thesecond system square sum V2_amp becomes a prescribed value (normalvalue). Accordingly, when the second system square sum V2_amp deviatesfrom the normal range including the normal value, it can be determinedthat abnormality occurred in the second system.

$\begin{matrix}{{{V2\_ amp} \approx {4 \times \{ {( {{KA}2 \times {\sin({\theta 2})}} )^{2} + ( {{KA}2 \times {\cos({\theta 2})}} )^{2}} \}}} = {{4 \times {KA}2^{2} \times \{ {{\sin({\theta 2})}^{2} + {\cos({\theta 2})}^{2}} \}} = {4 \times {KA}2^{2} \times 1}}} & (19)\end{matrix}$

On the other hand, in the case where the first period componentreduction processing (subtraction processing) is not performed unlikethe present embodiment, and the components of the first period aresuperimposed on the detection values of output signals of second systemtwo output windings, as shown in FIG. 9 , since the components of thefirst period are the same between the second system detection timings, avibration component of the first period TA is superimposed on the secondsystem square sum V2_amp, and the second system abnormalitydetermination cannot be performed with good accuracy.

The abnormality of second system includes abnormality of disconnectionof each winding 10B, 111B, 112B of the second system, abnormality of theinput and output circuit of each winding of the second system in thecontroller 50, abnormality of processing related to the second system ofthe controller 50, and the like.

The normal range of second system is set to a range between a lowerlimit value of second system MIN2 and an upper limit value of secondsystem MAX2 in which a normal value of the second system square sumV2_amp is included. For example, the lower limit value of second systemMIN2 is preliminarily set to a value obtained by multiplying acoefficient (for example, 0.9) smaller than 1 to the normal value of thesecond system square sum V2_amp; and the upper limit value of secondsystem MAX2 is preliminarily set to a value obtained by multiplying acoefficient (for example, 1.1) larger than 1 to the normal value of thesecond system square sum V2_amp. The normal range of second system isadjusted in accordance with the degree of abnormality to be determinedas abnormal.

Processing of the abnormality determination is explained using theflowchart of FIG. 11 . Processing of the flowchart of FIG. 11 isexecuted after calculating the second system square sum V2_amp at everythe second system detection timing.

In the step S31, the second system abnormality detection unit 56Bacquires the second system square sum V2_amp calculated by the secondsystem square sum calculation unit 55B. Then, in the step S32, thesecond system abnormality detection unit 56B determines whether or notthe second system square sum V2_amp is greater than or equal to thelower limit value of second system MIN2, and is less than or equal tothe upper limit value of second system MAX2. That is to say, the secondsystem abnormality detection unit 56B determines whether or not thesecond system square sum V2_amp is within the normal range of secondsystem.

When the second system abnormality detection unit 56B determines thatthe second system square sum V2_amp is not within the normal range ofsecond system in the step S32, it advances to the step S33 anddetermines that the abnormality of second system occurred. In thepresent embodiment, the second system abnormality detection unit 56Boutputs a second system abnormality signal ERR2, when determining thatthe abnormality of second system occurred. For example, the secondsystem abnormality signal ERR2 is transmitted to the external controller94 to which the second angle θ2 is transmitted. If the controller 50 andthe external controller 94 are integrated, the second system abnormalitysignal ERR2 is transmitted in the same controller.

On the other hand, when the second system abnormality detection unit 56Bdetermines that the second system square sum V2_amp is within the normalrange of second system in the step S32, it determines that theabnormality of second system does not occur, and ends processing.

<Another Example of Abnormality Determination Processing>

Another example of processing of abnormality determination is explainedusing the flowchart of FIG. 12 . Processing of the flowchart of FIG. 12is executed after calculating the second system square sum V2_amp atevery the second system detection timing.

In the step S41, the second system abnormality detection unit 56Bacquires the second system square sum V2_amp calculated by the secondsystem square sum calculation unit 55B. Then, in the step S42, thesecond system abnormality detection unit 56B determines whether or notthe second system square sum V2_amp is greater than or equal to thelower limit value of second system MIN2, and is less than or equal tothe upper limit value of second system MAX2. That is to say, the secondsystem abnormality detection unit 56B determines whether or not thesecond system square sum V2_amp is within the normal range of secondsystem.

When the second system abnormality detection unit 56B determines thatthe second system square sum V2_amp is not within the normal range ofsecond system in the step S42, it advances to the step S43 and increasesthe abnormality determination counter T2 by one. After that, it advancesto the step S44, and the second system abnormality detection unit 56Bdetermines whether or not the abnormality determination counter T2 isgreater than or equal to a preliminarily set abnormality determinationfrequency T2 ab.

When the second system abnormality detection unit 56B determines thatthe abnormality determination counter T2 is greater than or equal to theabnormality determination frequency T2 ab in the step S44, it advancesto the step S45 and determines that the abnormality of second systemoccurred. Then, the second system abnormality detection unit 56B outputsthe second system abnormality signal ERR2, when determining that theabnormality of second system occurred. When the second systemabnormality detection unit 56B determines that the abnormalitydetermination counter T2 is not greater than or equal to the abnormalitydetermination frequency T2 ab in the step S44, it determines that theabnormality of second system does not occur, and ends processing.

On the other hand, when the second system abnormality detection unit 56Bdetermines that the second system square sum V2_amp is within the normalrange of second system in the step S42, it advances to the step S46,after resetting the abnormality determination counter T2 to 0, endsprocessing.

In the example of the flowchart of FIG. 12 , when a case where thesecond system square sum V2_amp is not within the normal range of secondsystem occurs continuously the preliminarily set abnormalitydetermination frequency T2 ab or more, the second system abnormalitydetection unit 56B determines that abnormality occurred in the secondsystem.

In this way, by performing determination by the abnormalitydetermination frequency T2 ab, erroneous determination can be preventedfrom occurring due to noise component generated in the second systemsquare sum V2_amp. By determining that abnormality occurred when it isnot within the normal range continuously, accuracy of abnormalitydetermination can be improved.

In the step S46, the second system abnormality detection unit 56B maynot reset the abnormality determination counter T2 to 0, but may holdthe abnormality determination counter T2 to the previous value, or maydecrease the abnormality determination counter T2.

1-2-11. Second System Angle Calculation Unit

As shown in the next equation, the second system angle calculation unit54B calculates the second angle θ2 by calculating an arc tangent (an arctangent function) of a ratio between the output signal V1B_F of thesecond system first output winding and the output signal V2B_F of thesecond system second output winding after the first period componentreduction processing.

θ2=tan⁻¹(V1B_F/V2B_F)  (20)

As shown in the equation (15), the detection values of output signals ofthe second system two output windings V1B_F, V2B_F after the firstperiod component reduction processing correspond to the double values ofthe components of the second period V1B_TB, V2B_TB included in thedetection values, respectively. Therefore, as shown in the next equationin which the equation (15) is substituted in the equation (20), thesecond angle θ2 is calculated with good accuracy by the ratio of thecomponents of the second period V1B_TB, V2B_TB included in the detectionvalues.

$\begin{matrix}{{{\theta 2} \approx {\tan^{- 1}\{ {( {2 \times {V1B\_ TB}} )/( {2 \times {V2B\_ TB}} )} \}}} = {\tan^{- 1}( {{V1B\_ TB}/{V2B\_ TB}} )}} & (21)\end{matrix}$

It is only required that the setting values of the first period TA, thesecond period TB, the first system detection timing, the second systemdetection timing, the first system reduction processing interval ΔT1,and the second system reduction processing interval ΔT2 arepreliminarily set to become the predetermined relation between the firstsystem and the second system; the processing of the first system and theprocessing of the second system can be performed independently with eachother; and it is not necessary to perform synchronous control in realtime between the first system and the second system.

2. Embodiment 2

Next, the abnormality detection apparatus for resolver according toEmbodiment 2 will be explained. The explanation for constituent partsthe same as those in Embodiment 1 will be omitted. The basicconfiguration of the abnormality detection apparatus for resolveraccording to the present embodiment is the same as that of Embodiment 1.Embodiment 2 is different from Embodiment 1 in configuration of thesecond system output signal detection unit 52B, and the second systemreduction processing unit 53B.

Also in the present embodiment, the second system output signaldetection unit 52B detects periodically the output signals V1B, V2B ofthe second system two output windings 111B, 112B at preliminarily setdetection timing (the second system detection timing).

<Problem Due to Magnetic Interference Between Systems>

As showing an example of the output signal V1B of the second systemfirst output winding in FIG. 13 , the components of the first periodinduced by electromagnetic induction of the magnetic flux of the firstperiod TA excited in the first system excitation winding 10A aresuperimposed on each of the output signals V1B, V2B of the second systemtwo output windings 111B, 112B, due to the magnetic interference betweensystems. The output signal V1B of the second system first output windingis shown in the upper row graph of FIG. 13 ; the component of the secondperiod V1B_TB induced by electromagnetic induction of the magnetic fluxof the second system excitation winding 10B included in the outputsignal V1B of the second system first output winding is shown in themiddle graph; and the component of the first period V1B_TA induced byelectromagnetic induction of the magnetic flux of the first systemexcitation winding 10A included in the output signal V1B of the secondsystem first output winding is shown in the lower row graph. The outputsignal V1B of the second system first output winding becomes a signalobtained by totaling the component of the second period V1B_TB and thecomponent of the first period V1B_TA, and if the second system squaresum V2_amp is calculated with these signals, error will occur.Therefore, in order to suppress the error of the second system squaresum V2_amp, it is necessary to reduce the component of the first periodV1B_TA from the output signal V1B of the second system first outputwinding.

<First Period Component Reduction Processing>

Also in the present embodiment, the second system reduction processingunit 53B performs a first period component reduction processing whichreduces component of the first period, to the detection values of outputsignals of second system two output windings V1B_S, V2B_S.

In the present embodiment, unlike Embodiment 1, the first periodcomponent reduction processing is performed based on a principleexplained in the following. As shown in the lower row graph of FIG. 13 ,in the component of the first period V1B_TA of the output signal of thesecond system first output winding, the phase is reversed and the signof plus or minus is reversed in a period (for example, half period TA/2of the second period) obtained by adding an integral multiple of thefirst period TA to a half period TA/2 of the first period.

Then, as the first period component reduction processing, the secondsystem reduction processing unit 53B adds the detection values of outputsignals of second system two output windings V1B_S, V2B_S detected atthis time detection timing, and the detection values of output signalsof second system two output windings V1B_Sold, V2B_Sold detected at thedetection timing earlier by the second system reduction processinginterval ΔT2 than this time detection timing. The second systemreduction processing interval ΔT2 is set to an interval obtained byadding an integral multiple of the first period TA to the half periodTA/2 of the first period, as shown in the next equation. Herein, X is aninteger greater than or equal to 0. In the present embodiment, X is setto 0, and the second system reduction processing interval ΔT2 is set tothe half period TA/2 of the first period.

ΔT2=TA/2+TA×X  (22)

Then, similar to Embodiment 1, then, the second system square sumcalculation unit 55B calculates the second system square sum V2_ampwhich is a sum of square values of the detection values of outputsignals of second system two output windings V1B_F, V2B_F afteraddition. Then, the second system abnormality detection unit 56Bdetermines abnormality of second system, based on whether or not thesecond system square sum V2_amp is within a preliminarily set normalrange of second.

According to this configuration, the two components of the first periodwhose signs of plus or minus are reversed with each other are added, andthe two components of the first period are canceled with each other.Accordingly, in the detection values V1B_F, V2B_F of the output signalsof the second system two output windings after addition, the componentsof the first period are reduced. Then, using the components of thesecond period of the second system in which the component of the firstperiod of the first system was reduced, the second system square sumV2_amp used for second system abnormality determination can becalculated with good accuracy.

In the present embodiment, as shown in FIG. 13 , the second systemoutput signal detection unit 52B detects periodically the output signalsof second system two output windings V1B, V2B at two timings TM1, TM2which become before-and-after symmetrical with respect to a referencetiming TM0 when the AC voltage VRB of the second period TB applied tothe second system excitation winding 10B becomes the maximum value orthe minimum value.

An interval between two timings which become before-and-after symmetryis set to the second system reduction processing interval ΔT2.Therefore, as shown in the next equation, an interval ΔTM12 between eachof before-and-after two timings TM1, TM2 and the reference timing TM0 isset to the half of the second system reduction processing interval ΔT2.

ΔTM12=ΔT2/2  (23)

Then, the second system reduction processing unit 53B adds the detectionvalues of output signals of second system two output windings detectedat the two timings TM1, TM2 which become before-and-after symmetry, witheach other; and calculates the second angle θ2 and the second systemsquare sum V2_amp, based on the detection values of output signals ofsecond system two output windings V1B_F, V2B_F after addition

According to this configuration, as shown in FIG. 13 , the components ofthe second period included in the detection values of output signals ofsecond system two output windings detected at two timings have the samephase, and become the equivalent values with the same sign of plus orminus. Since the interval between two timings TM1, TM2 is set to thesecond system reduction processing interval ΔT2, in the components ofthe first period included in the detection values of output signals ofsecond system two output windings detected at two timings TM1, TM2, thephases are reversed and the signs of plus or minus are reversed.Therefore, the detection values V1B_F, V2B_F of the output signals ofthe second system two output windings after addition correspond to thedouble values of the components of the second period V1B_TB, V2B_TBincluded in the detection values, respectively.

V1B_F≈2×V1B_TB

V2B_F≈2×V2B_TB  (24)

Accordingly, in the equation (26) and the equation (27) described below,since a square value of the detection value V1B_F of the output signalof the second system first output winding after addition processing anda square value of the detection value V2B_F of the output signal of thesecond system second output winding after addition processing are added,it corresponds to a 4 times value of the square sum of the components ofthe second period V1B_TB, V2B_TB, and the second system square sumV2_amp can be calculated with good accuracy, based on the components ofthe second period of the second system in which the components of thefirst period of the first system were reduced.

The second system reduction processing unit 53B is constituted, forexample, as shown in FIG. 14 . The second system reduction processingunit 53B is provided with a first delay device 53B1 which delays thedetection value V1B_S of the output signal of the second system firstoutput winding by the second system reduction processing interval ΔT2,and outputs; adds the detection value V1B_S of the output signal of thesecond system first output winding and the output V1B_Sold of the firstdelay device 53B1, at the timing TM2 after the reference timing TM0; andcalculates the detection value V1B_F of the output signal of the secondsystem first output winding after the first period component reductionprocessing. Similarly, the second system reduction processing unit 53Bis provided with a second delay device 53B2 which delays the detectionvalue V2B_S of the output signal of the second system second outputwinding by the second system reduction processing interval ΔT2, andoutputs; adds the detection value V2B_S of the output signal of thesecond system second output winding and the output V2B_Sold of thesecond delay device 53B2, at the timing TM2 after the reference timingTM0; and calculates the detection value V2B_F of the output signal ofthe second system second output winding after the first period componentreduction processing.

In the present embodiment, as shown in the next equation, the secondperiod TB is set to twice of the first period TA. The second systemreduction processing interval ΔT2 is set to the half period TA/2 of thefirst period. Therefore, the interval ΔTM12 between each ofbefore-and-after two timings TM1, TM2 and the reference timing TM0 isset to 1/4 period TA/4 of the first period.

TB=TA×2

ΔT2=TA/2

ΔTM12=TA/4  (25)

The second system output signal detection unit 52B detects the outputsignals of second system two output windings V1B, V2B at every 1/4period TB/4 of the second period; and each detection timing is set so asto become before-and-after symmetrical with respect to the referencetiming TM0 when the AC voltage VRB of the second period TB becomes themaximum value or the minimum value.

<Calculation of Second System Square Sum>

Similarly to Embodiment 1, the second system square sum calculation unit55B calculates the second system square sum V2_amp which is a sum ofsquare values of the detection values of output signals of second systemtwo output windings V1B_F, V2B_F after the first period componentreduction processing, as shown in the next equation.

V2_amp=V1B_F ² +V2B_F ²  (26)

As shown in the equation (24), the detection values of output signals ofthe second system two output windings V1B_F, V2B_F after the firstperiod component reduction processing correspond to the double values ofthe components of the second period V1B_TB, V2B_TB included in thedetection values, respectively. Therefore, as shown in the next equationin which the equation (24) is substituted in the equation (26), itcorresponds to a 4 times value of the square sum of the components ofthe second period V1B_TB, V2B_TB. Therefore, using the components of thesecond period V1B_TB, V2B_TB of the second system in which the componentof the first period V1B_TA, V2B_TA of the first system was reduced, thesecond system square sum V2_amp used for second system abnormalitydetermination can be calculated with good accuracy.

$\begin{matrix}{{{V2\_ amp} \approx {( {2 \times {V1B\_ TB}} )^{2} + ( {2 \times {V2B\_ TB}} )^{2}}} = {4 \times \{ {{V1B\_ TB}^{2} + {V2B\_ TB}^{2}} \}}} & (27)\end{matrix}$

3. Embodiment 3

Next, the abnormality detection apparatus for resolver according toEmbodiment 3 will be explained. The explanation for constituent partsthe same as those in each of Embodiments 1 or 2 will be omitted. Thebasic configuration of the abnormality detection apparatus for resolveraccording to the present embodiment is the same as that of Embodiment 1.But, the configuration of the resolver 1 is different from Embodiment 1or 2. FIG. 15 is a schematic configuration diagram of the angledetection apparatus according to the present embodiment.

Similarly to Embodiment 1, the resolver 1 is provided with the firstsystem excitation winding 10A, the first system two output windings111A, 112A, the second system excitation winding 10B, and the secondsystem two output windings 111B, 112B. A magnetic interference occursbetween the first system windings and the second system windings.

However, in the present embodiment, unlike Embodiment 1 and 2, as theschematic diagram of the resolver 1 is shown in FIG. 16 , the firstsystem excitation winding 10A and the first system two output windings111A, 112A are wound around the first system stator 13A; and the secondsystem excitation winding 10B and the second system two output windings111B, 112B are wound around the second system stator 13B. The firstsystem stator 13A and the second system stator 13B are arranged adjacentto each other in the axial direction; and a magnetic interference occursbetween the first system windings and the second system windings. InFIG. 16 , the teeth and the windings of the first system stator 13A, andthe teeth and the windings of the second system stator 13B are omittedin figure.

The first system stator 13A and the second system stator 13B arecoaxially arranged adjacent to each other in the axial direction; andthe rotor 14 formed integrally is arranged in the radial-direction innerside of the first system stator 13A and the second system stator 13B.The rotor 14 is provided with a plurality of projection parts which arearranged equally in the circumferential direction on the peripheral partof the rotor. In the present embodiment, the rotor part located in theradial-direction inner side of the first system stator 13A and the rotorpart located in the radial-direction inner side of the second systemstator 13B have the same shape of the projection parts. The rotor partof the radial-direction inner side of the first system stator 13A andthe rotor part of the radial-direction inner side of the second systemstator 13B may have the different shapes and the different numbers ofthe projection parts with each other; and these may be the differentbodies connected so as to rotate integrally.

The first system stator 13A is provided with a plurality of teetharranged equally in the circumferential direction. The first systemfirst output winding 111A and the first system second output winding112A are distributed and wound around each teeth of the first systemstator 13A so that the amplitudes of those induced AC voltages aremutually different 90 degrees in the electrical angle. The second systemstator 13B is provided with a plurality of teeth arranged equally in thecircumferential direction. The second system first output winding 111Band the second system second output winding 112B are distributed andwound around each teeth of the second system stator 13B so that theamplitudes of those induced AC voltages are mutually different 90degrees in the electrical angle. The second system excitation winding10B is distributed and wound around each teeth of the second systemstator 13B. The teeth number of the first system stator 13A and theteeth number of the second system stator 13B may be the same numbers, ormay be the different numbers.

Even using the configuration of this kind resolver 1, by performing thesimilar processing as the controller 50 of Embodiment 1 or 2, even ifthe magnetic interference between systems occurs, the first angle θ1,the second angle θ2, the first system square sum V1_amp and the secondsystem square sum V2_amp are detected with good accuracy.

4. Other Embodiments

Lastly, other embodiments of the present disclosure will be explained.Each of the configurations of embodiments to be explained below is notlimited to be separately utilized but can be utilized in combinationwith the configurations of other embodiments as long as no discrepancyoccurs.

(1) The first system and the second system may be replaced. That is tosay, the first system of each of above embodiments may be set to thesecond system; and the second system of each of above embodiments may beset to the first system.

(2) In each of the above-mentioned embodiments, there was explained thecase where the abnormality of first system is determined based on thefirst system square sum V1_amp, and the abnormality of second system isdetermined based on the second system square sum V2_amp. However,embodiments of the present disclosure are not limited to the foregoingcase. That is to say, the abnormality of first system may be determinedbased on a square root of first system square sum V1_amp, and theabnormality of second system may be determined based on a square root ofthe second system square sum V2_amp.

(3) In each of the above-mentioned embodiments, there was explained thecase where the first system reduction processing unit 53A performs theaddition processing of this time detection value and the detection valuebefore the first system reduction processing interval ΔT1, as the secondperiod component reduction processing which reduces the component of thesecond period included in the detection values of output signals offirst system two output windings; and the second system reductionprocessing unit 53B performs the subtraction processing or the additionprocessing of this time detection value and the detection value beforethe second system reduction processing interval ΔT2, as the first periodcomponent reduction processing which reduces the component of the firstperiod included in the detection values of output signals of secondsystem two output windings. However, embodiments of the presentdisclosure are not limited to the foregoing case. That is to say, thefirst system reduction processing unit 53A may perform a band reductionfilter processing such as a high pass filter processing or a band stopfilter processing which reduces the component of the second period, asthe second period component reduction processing. The second systemreduction processing unit 53B may perform a band reduction filterprocessing such as a low pass filter processing or a band stop filterprocessing which reduces the component of the first period, as the firstperiod component reduction processing.

(4) In each of the above-mentioned Embodiments, there been explained thecase where the one controller 50 is provided with the processing units51A to 56A of the first system, and the processing units 51B to 56B ofthe second system. However, embodiments of the present disclosure arenot limited to the foregoing case. That is to say, a controller of thefirst system may be provided with the processing units 51A to 56A of thefirst system, and a controller of the second system may be provided withthe processing units 51B to 56B of the second system, or a plurality ofcontrollers may be distributedly provided with each processing units 51Ato 56B of the first system and the second system.

(5) In each of the above-mentioned embodiments, there was explained thecase where the first system output signal detection unit 52A detects theoutput signals of first system two output windings V1A, V2A at every thefirst period TA when the excitation AC voltage VRA becomes the maximumvalue. However, embodiments of the present disclosure are not limited tothe foregoing case. That is to say, the first system output signaldetection unit 52A may detect the output signals of first system twooutput windings V1A, V2A at every the first period TA when theexcitation AC voltage VRA becomes the minimum value, or may detect atevery the first period TA when the excitation AC voltage VRA becomesother than the maximum value and the minimum value as mentioned above.Alternatively, the first system output signal detection unit 52A maydetect at every the half period TA/2 of the first period when theexcitation AC voltage VRA becomes the maximum value or the minimumvalue. Alternatively, the first system output signal detection unit 52Amay the detect output signals of first system two output windings V1A,V2A at every period (for example, a period obtained by dividing thefirst system reduction processing interval ΔT1 by an integer greaterthan or equal to one) which is different from the first period TA andthe half period TA/2 of the first period. Also in these cases, the firstdelay device 53A1 and the second delay device 53A2 of the first systemreduction processing unit 53A delays the input signal by the firstsystem reduction processing interval ΔT1 and outputs.

(6) In above-mentioned Embodiment 1, there was explained the case wherethe second system output signal detection unit 52B detects the outputsignals of second system two output windings V1B, V2B at every the halfperiod TB/2 of the second period when the excitation AC voltage VRBbecomes the maximum value or the minimum value. However, embodiments ofthe present disclosure are not limited to the foregoing case. That is tosay, as mentioned above, the second system output signal detection unit52B may detect at every half period TB/2 of the second period when theexcitation AC voltage VRB becomes other than the maximum value and theminimum value. Alternatively, the second system output signal detectionunit 52B may the detect output signals of second system two outputwindings V1B, V2B at every period (for example, a period obtained bydividing the second system reduction processing interval ΔT2 by aninteger greater than or equal to one) which is different from the halfperiod TB/2 of the second period. Also in these cases, the first delaydevice 53B1 and the second delay device 53B2 of the second systemreduction processing unit 53B delays the input signal by the secondsystem reduction processing interval ΔT2 and outputs.

(7) In above-mentioned Embodiment 2, there was explained the case wherethe second system output signal detection unit 52B detects the outputsignals V1B, V2B of the second system two output windings at every 1/4period TA/4 of the first period; and each detection timing is set so asto become before-and-after symmetrical with respect to the referencetiming TM0 when the AC voltage VRB of the second period TB becomes themaximum value or the minimum value. However, embodiments of the presentdisclosure are not limited to the foregoing case. That is to say, thesecond system output signal detection unit 52B may detect periodicallythe output signals V1B, V2B of the second system two output windings attwo timings which become before-and-after symmetrical with respect to areference timing TM0 when the excitation AC voltage VRB becomes themaximum value. Alternatively, the second system output signal detectionunit 52B may detect periodically the output signals V1B, V2B of thesecond system two output windings at two timings which becomebefore-and-after symmetrical with respect to a reference timing TM0 whenthe excitation AC voltage VRB becomes the minimum value. As long as theinterval between two timings which become before-and-after symmetry isset to the second system reduction processing interval ΔT2, it may beset to an interval other than 1/4 period TB/4 of the second period. Alsoin these cases, the first delay device 53B1 and the second delay device53B2 of the second system reduction processing unit 53B may delay theinput signal by the second system reduction processing interval ΔT2 andoutput; and the second system reduction processing unit 53B may performthe addition processing at the later timing TM2 with respect to thereference timing TM0 and calculate the detection values of outputsignals of second system two output windings V1B_F, V2B_F afteraddition.

(8) As the angle detection apparatus for a motor which is provided withtwo sets of three-phase windings and inverters, the angle detectionapparatus according to the present disclosure may be used. This kind ofdual system motor is provided in an electric power steering apparatus,for example. The configuration of the first system of the angledetection apparatus of the present disclosure is assigned to the controlsystem of the first set of three-phase winding and inverter, and thefirst angle θ1 is used for it. The configuration of the second system ofthe angle detection apparatus of the present disclosure is assigned tothe control system of the second set of three-phase winding andinverter, and the second angle 02 is used for it. Then, when theabnormality of first system of the angle detection apparatus isdetected, control of the first set of three-phase winding and inverteris stopped. When the abnormality of second system of the angle detectionapparatus is detected, control of the second set of three-phase windingand inverter is stopped. Since it is not necessary to synchronize thefirst system and the second system in the angle detection apparatus ofthe present disclosure, it may be configure that the first set ofthree-phase winding and inverter, and the first system of angledetection apparatus are controlled by a first controller (CPU), and thesecond set of three-phase winding and inverter, and the second system ofangle detection apparatus are controlled by a second controller (CPU).Accordingly, system including the angle detection apparatus can be maderedundant, and reliability can be improved.

Although the present disclosure is described above in terms of variousexemplary embodiments and implementations, it should be understood thatthe various features, aspects and functionality described in one or moreof the individual embodiments are not limited in their applicability tothe particular embodiment with which they are described, but instead canbe applied, alone or in various combinations to one or more of theembodiments. It is therefore understood that numerous modificationswhich have not been exemplified can be devised without departing fromthe scope of the present disclosure. For example, at least one of theconstituent components may be modified, added, or eliminated. At leastone of the constituent components mentioned in at least one of thepreferred embodiments may be selected and combined with the constituentcomponents mentioned in another preferred embodiment.

REFERENCE SIGNS LIST

1 Resolver, 10A First system excitation winding, 10B Second systemexcitation winding, 111A, 112A First system two output windings, 111B,112B Second system two output windings, 51A First system excitationunit, 52A First system output signal detection unit, 53A First systemreduction processing unit, 54A First system angle calculation unit, 55AFirst system square sum calculation unit, 56A First system abnormalitydetection unit, 51B Second system excitation unit, 52B Second systemoutput signal detection unit, 53B Second system reduction processingunit, 54B Second system angle calculation unit, 55B Second system squaresum calculation unit, 56B Second system abnormality detection unit, TAFirst period, TB Second period, V1_amp First system square sum, V2_ampSecond system square sum, ΔT1 First system reduction processinginterval, ΔT2 Second system reduction processing interval, V1A_S, V2A_SDetection values of the first system two output signals, V1A_F, V2A_FDetection values of the first system two output signals after the secondperiod component reduction processing, V1A_TA, V2A_TA Components of thefirst period included in the output signals of first system two outputwindings, V1A_TB, V2A_TB Components of the second period included in theoutput signals of first system two output windings, V1B_S, V2B_SDetection values of the second system two output signals, V1B_F, V2B_FDetection values of the second system two output signals after the firstperiod component reduction processing, V1B_TA, V2B_TA Components of thefirst period included in the output signals of second system two outputwindings, V1B_TB, V2B_TB Components of the second period included in theoutput signals of second system two output windings

1. An abnormality detection apparatus for resolver comprising: aresolver that is provided with a first system excitation winding, firstsystem two output windings, a second system excitation winding, andsecond system two output windings, in which magnetic interference occursbetween a first system and a second system; a first system exciter thatapplies AC voltage of a first period to the first system excitationwinding; a second system exciter that applies the AC voltage of a secondperiod different from the first period, to the second system excitationwinding; a first system output signal detector that detects periodicallyoutput signals of the first system two output windings at preliminarilyset detection timing; a first system reduction processor that performs asecond period component reduction processing which reduces component ofthe second period, to detection values of the output signals of thefirst system two output windings; a first system square sum calculatorthat calculates a first system square sum which is a sum of squarevalues of the detection values of output signals of first system twooutput windings after the second period component reduction processing;and a first system abnormality detector that determines abnormality offirst system, based on whether or not the first system square sum iswithin a preliminarily set normal range of first system.
 2. Theabnormality detection apparatus for resolver according to claim 1,wherein, when a case where the first system square sum is not within thenormal range of first system occurs continuously a preliminarily setabnormality determination frequency or more, the first systemabnormality detector determines that abnormality occurs in the firstsystem.
 3. The abnormality detection apparatus for resolver according toclaim 1, wherein the second period is set longer than the first period,wherein the first system reduction processor, as the second periodcomponent reduction processing, adds the detection values of outputsignals of first system two output windings detected at this timedetection timing, and the detection values of output signals of firstsystem two output windings detected at the detection timing earlier by afirst system reduction processing interval than this time detectiontiming, wherein when setting the second period to TB, the first systemreduction processing interval is set to TB/2+TB×M (M is an integergreater than or equal to 0), and wherein the first system square sumcalculator calculates the first system square sum which is a sum ofsquare values of the detection values of output signals of first systemtwo output windings after addition.
 4. The abnormality detectionapparatus for resolver according to claim 3, wherein when setting thefirst period to TA, the second period is set to TA×2×N (N is greaterthan or equal to 1).
 5. The abnormality detection apparatus for resolveraccording to claim 3, wherein the first system output signal detectordetects the output signals of the first system two output windings at atiming when the AC voltage of the first period applied to the firstsystem excitation winding becomes the maximum value or the minimumvalue.
 6. The abnormality detection apparatus for resolver according toclaim 1, further comprising: a second system output signal detector thatdetects periodically output signals of the second system two outputwindings at preliminarily set detection timing; a second systemreduction processor that performs a first period component reductionprocessing which reduces component of the first period, to detectionvalues of the output signals of second system two output windings; and asecond system square sum calculator that calculates a second systemsquare sum which is a sum of square values of the detection values ofoutput signal of second system two output windings after the firstperiod component reduction processing; and a second system abnormalitydetector that determines abnormality of second system, based on whetheror not the second system square sum is within a preliminarily set normalrange of second system.
 7. The abnormality detection apparatus forresolver according to claim 6, wherein, when a case where the secondsystem square sum is not within the normal range of second system occurscontinuously a preliminarily set abnormality determination frequency ormore, the second system abnormality detector determines that abnormalityoccurs in the second system.
 8. The abnormality detection apparatus forresolver according to claim 6, wherein the second system reductionprocessor performs, as the first period component reduction processing,a subtraction processing which calculates differences between thedetection values of output signal of second system two output windingsdetected at this time detection timing and the detection values ofoutput signal of second system two output windings detected at thedetection timing earlier by a second system reduction processinginterval than this time detection timing, wherein when setting the firstperiod to TA, the second system reduction processing interval is set toTA×P (P is an integer greater than or equal to 1), and wherein thesecond system square sum calculator calculates the second system squaresum which is a sum of square values of the detection values of outputsignals of second system two output windings after subtractionprocessing.
 9. The abnormality detection apparatus for resolveraccording to claim 8, wherein when setting the first period to TA, thesecond period is set to TA×2×N (N is greater than or equal to 1); andwherein when setting the second period to TB, the second systemreduction processing interval is set to TB/2+TB×L (L is an integergreater than or equal to 0).
 10. The abnormality detection apparatus forresolver according to claim 6, wherein the second system output signaldetector detects the output signals of the second system two outputwindings at a timing when the AC voltage of the second period applied tothe second system excitation winding becomes the maximum value or theminimum value.
 11. The abnormality detection apparatus for resolveraccording to claim 6, wherein the second system reduction processor, asthe first period component reduction processing, adds the detectionvalues of output signals of second system two output windings detectedat this time detection timing, and the detection values of outputsignals of second system two output windings detected at the detectiontiming earlier by a second system reduction processing interval thanthis time detection timing, wherein the second system square sumcalculator calculates the second system square sum which is a sum ofsquare values of the detection values of output signals of second systemtwo output windings after addition, and wherein when setting the firstperiod to TA, the second system reduction processing interval is set toTA/2+TA×X (X is an integer greater than or equal to 0).
 12. Theabnormality detection apparatus for resolver according to claim 11,wherein the second system output signal detector detects periodicallythe output signals of second system two output windings at two timingswhich become before-and-after symmetrical with respect to a referencetiming when the AC voltage of the second period applied to the secondsystem excitation winding becomes the maximum value or the minimumvalue, wherein an interval of the two timings is set to the secondsystem reduction processing interval, and wherein the second systemreduction processor adds the detection values of output signal of secondsystem two output windings detected at the two timings with each other.13. The abnormality detection apparatus for resolver according to claim1, wherein the first system excitation winding, the first system twooutput windings, the second system excitation winding, and the secondsystem two output windings are wound around the same one stator.
 14. Theabnormality detection apparatus for resolver according to claim 1,wherein the first system excitation winding and the first system twooutput windings are wound around a first system stator; and the secondsystem excitation winding and the second system two output windings arewound around a second system stator which adjoins the first systemstator in an axial direction.